It might be too late to do this project as a Christmas gift idea. I worked on it this weekend. But still, it may be a good Valentine's Day present idea. Just buy a fabric with heart or valentine motives.
You will find the instructions for this project on my favorite sewing book SEW (Sew Everything Workshop). There is a pattern included and it is described step by step at page 134.
It took me about an hour divided in two days...20 minutes Saturday morning. Then I went shopping. Came back at night, started again. Continued Sunday. I am becoming the queen of procrastination. :P
This is the third pair of boxers I make from this pattern and sincerely it is not an easy project since every time I start sewing it I need to have the book at hand. But it is worth the results!
Love the reindeer.